High speed free-space optical communications

ABSTRACT

High power, high speed VCSEL arrays are employed in unique configurations of arrays and sub-arrays. Placement of a VCSEL array behind a lens allows spatial separation and directivity. Diffusion may be employed to increase alignment tolerance. Intensity modulation may be performed by operating groups of VCSEL emitters at maximum bias. Optical communications networks with high bandwidth may employ angular, spatial, and/or wavelength multiplexing. A variety of network topologies and bandwidths suitable for the data center may be implemented. Eye safe networks may employ VCSEL emitters may be paired with optical elements to reduce optical power density to eye safe levels.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/594,714, filed Aug. 24, 2012, which claims benefit under 35 U.S.C. §119(e) of Provisional Application No. 61/528,119, filed Aug. 26, 2011,and of Provisional Application No. 61/671,036, filed Jul. 12, 2012, eachof which are incorporated herein by reference in their entirety.

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/077,769, filed Mar. 31, 2011, now U.S. Pat. No. 8,848,757,issued on Sep. 30, 2014, which is a continuation of U.S. patentapplication Ser. No. 12/707,657, filed Feb. 17, 2010, now U.S. Pat. No.7,949,024, issued on May 24, 2011, which claims benefit under 35 U.S.C.§ 119(e) of Provisional Application No. 61/153,190, filed Feb. 17, 2009.

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/970,880, filed Dec. 16, 2010, now U.S. Pat. No. 8,613,536,issued on Dec. 24, 2013, which claims benefit under 35 U.S.C. § 119(e)of Provisional Application No. 61/288,269, filed Dec. 19, 2009, each ofwhich are incorporated herein by reference in their entirety.

BACKGROUND

The bandwidth of transmitted data, and the range at which this data canbe conveyed in open air has been dependent on technologies that involveslower single or arrayed high power semiconductor laser transmitters orcombinations of such transmitters with optical modulators and/or opticalamplifiers, or through the use of multiple wavelengths in combinationwith the previous mentioned components to achieve a high bandwidth ratefor free space optical communications over distances farther than a fewmeters. To date the complexities involved in implementing thesetechnologies have become extremely cost prohibitive especially for ashort distance, in meters, for localized systems Available link budgetor available power from the emitter is another cost consideration, as isthe alignment and detection issues, which become more complicated andexpensive. A cost effective wireless optical transmitter with plenty oflink budget would be desirable. While vertical-cavity surface-emitting(“VCSEL”) arrays can produce the optical power necessary for thedistances mentioned above, and are much more cost effective, existingVCSEL arrays have not been able to produce the extremely high bandwidths(typically associated with single VCSEL devices) that are necessary.

In short distance optical communications, between adjacent transceiversand transceivers on circuit boards, using a fiber configuration limitsalignment of a fiber to a laser aperture. This alignment is typicallyachieved through the use of mechanically assembled components that addsize and cost of manufacturing, and the problem is compounded withmultiple fibers. Free space optical designs based on low amounts ofpower in the link budget means that achievable tolerances requireextreme mechanical board to board alignments which add cost with moreelaborate mechanical connector designs. Again, single VCSEL devices arebest suited for the bandwidth and cost structure, but lack the necessarypower and limit alignment to near unachievable tolerances.

SUMMARY

The related applications illustrate how VCSEL arrays may be fabricatedand tested with results that are superior to the state of the art whenpower and speed are considered. Due to the greater configurationflexibility in terms of design and packaging possible with VCSEL arrays,unique configurations such as arrays of sub-arrays, multiple wavelengtharrays of arrays and patterned shapes can be easily realized allowingthe optical path to be easily and quickly scanned without mechanicalmeans, and shaped according to the array configuration or to havemultiple possible links increasing the capabilities. The ability toproduce cost effective high speed and high power arrays using thesetechnologies creates unique opportunities for cost effective high speedoptical wireless communications.

Also, high speed optical communications between adjacent circuit boardshas conventionally been achieved using a fiber optic or multiple fibertransceiver or wavelength-division multiplexing of multiple channels ofdata into a single optical fiber configuration or a semiconductor laserfree space optical transceiver configuration. In either of theseconfigurations, it is necessary to deliver sufficient energy from theemitter to the detector to achieve minimum signal-to-noise ratio at thedesired bandwidth. A successful design starts with the available poweror link budget, then calculates all of the losses incurred in the systemand ends with sufficient power density at the detector. High speeddetectors are smaller and thereby require more power density to maintainsufficient signal to noise levels. One of the significant losses in thecalculation of the link budget is alignment loss of an emitter todetector. The reliability of the system is highly dependent upon theamount of power available from the emitter to overcome the alignmentissues and other system losses.

Optical communications between adjacent circuit boards offer manybenefits including higher bandwidths than what is available with copperconnections. A free space optical arrangement would normally bepreferred over a fiber system due to the simplicity of components.However, in a free space system, accommodations must be made to accountfor both translational and angular misalignments between the transmitterand the receiver. In addition, laser safety consideration should betaken into account. Typically free space configurations are limited bylow power devices or link budgets that require expensive or precisionmechanical connectors or expensive packaging configurations. Theembodiments disclosed here employ technology disclosed in the relatedapplications, including commonly-assigned U.S. Pat. No. 7,949,024 toenable high power arrays of VCSEL devices that operate at very highbandwidths. With the added power or link budget available from theselaser sources, the loose alignment tolerances enable a dramatic designchange which allows small, high speed, cost effective free space simplexor duplex single or parallel channels that increase total bandwidth tolevels that have previously been unachievable in a cost effectivemanner.

Optical communication may also provide benefits to the data center. Manyof the impediments to line of sight communication, such as particulatematter in the atmosphere, are minimal in the data center environment.Greater precision in beam alignment is also achievable. Embodiments ofthe invention described herein are capable of leveraging these factorsto achieve unprecedented bandwidth levels at reasonable cost.Furthermore, the use of optical communications drastically reduces theamount of cabling required in the data center, reducing complexity andmaintenance costs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a single, one-channel transmitter and receiver pair.

FIG. 2 depicts a pair of matching multi-channel transceivers.

FIG. 3 depicts a 32-bit emitter chip comprising both emitters anddetectors.

FIG. 4 depicts an arrangement of sub-clusters useful for intensitymodulation.

FIG. 5 depicts a free space optical switch in a data center rack.

FIG. 6 depicts a structure for mounting a free space optical switch ortransceiver above a surface.

FIG. 7 depicts an embodiment employing frequency, angular, and spatialmultiplexing.

FIG. 8 depicts an embodiment of a high speed free space optical switch.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Array Clusters

An embodiment is disclosed that includes a single, duplex, 1D or 2Darray of small clusters of high power and high speed free-space laserbeams (such as those described in the related applications) onto acorresponding array of detectors on the receiving side in a symmetricfashion so as to facilitate a mutual pair of inward-facing devices toprovide full bi-directional communications. The clusters may be wired inparallel, or may be broken up into binary-weighted sub-groups which aredriven individually and in parallel. In either case, the beams from eachindividual cluster may be blended using a holographic optical diffusingelement which spreads the beam bundle to a collimating lens for transferto the collection lens of each corresponding detector. This alsofacilitates a board-to-board “daisy chaining” scheme to enable abus-like data architecture shared by all the boards.

FIG. 1 depicts a single, one-channel transmitter/receiver pair from thesystem in FIG. 2 or any similar design. The emitter may be on a chipfrom an epitaxial grown GaAs wafer which has been processed according tothe concept set forth in U.S. Pat. No. 7,949,024, with a cluster of twoor more VCSEL elements (100) may be electrically connected in paralleland driven by a single high speed driver. In an embodiment, the beamfrom each of the elements impinges upon the surface of an opticaldiffusing element (102) such as a holographic optical diffuser. Such adiffuser has the advantage of providing good optical power uniformityover the resulting beam spread and high transmission efficiency. Thediffuse cone from each of the VCSEL elements impinges upon the back of alens (104), whose focal length equals that of the distance from thediffusing surface to the principal plane of the lens. The beams thatemerge from the lens are a combination of the beams from the individualelements, and they are not coherent, which reduces laser speckleeffects. The bundle appears to the receiver as a single, semi-collimateddisc of light (106). If this disc is of sufficient diameter incomparison to its optical power, then laser safety criteria may moreeasily be met by treating the bundle as an “extended source”.

The size of this bundle at the receiver collection lens (108) mayunder-fill, match, or over-fill the size of the collecting lens,depending upon the amount of translational tolerance desired.

As this bundle impinges upon the receiver collection lens, it is focusedto a small spot behind the surface of the detector (110) so as to form ablur circle (112) at the detector plane. This allows a certain amount oftilt or translational tolerance of the receiver to the optical axis ofthe transmitter while still delivering sufficient optical power at thedetector plane to meet the link budget. A trade-off can thereby be madebetween angular tolerance and optical power to provide sufficient linkbudget energy within the blur circle.

FIG. 2 depicts a pair of matching multi-channel transceivers in aconfiguration whereby a single GaAs emitter chip (200) is situatedbetween two or more detector/amplifier pair elements (202) on a sharedsubstrate (204). An identical emitter array and detector/amplifier array(206) having a second shared substrate (208) is situated facing, on theoptical axis, but at some distance away from the first substrate (204).A symmetric system of transmitters and receivers may thus be constructedto provide simultaneous, multi-channel communications between the twosymmetric and facing substrates.

The emitter chip (200) is comprised of two or more high speed VCSELclusters, each cluster driven by its own high speed current controllingcircuit. As already illustrated in FIG. 1, the transmitter lens issituated after the diffuser such that each different cluster will createits own semi-collimated beam bundle which is angularly shifted from thebeam bundles from the other clusters. In this way, each bundle may bedirected to its matching receiver collection lens at the periphery ofthe corresponding receiver substrate. The receiver lens at the peripheryof the substrate is offset towards the center of the substrate toaccommodate the fact that the transmitter beam is arriving from near thecenter of the corresponding substrate, and not parallel to the opticalaxis between the substrates. The scheme may be extended to twodimensions whereby the emitter chip is a 2D array of m×n clusters, andthe detector/amplifier array is a ring of elements surrounding theemitter chip.

FIG. 3 represents a top view of one of the matching pairs which have a32 bit configuration. This drawing illustrates the density possible witha transceiver which has 32 clustered emitter sources arrayed on a chip(300) in a pattern that would look like a square donut with the clustersformed around the square area in the middle (310). Many otherconfigurations could be used as described herein. The illustrated designof an embodiment allows a dense, but small emitter chip. The emitterchip would be located in the square area (310), while allowing manydetectors and support chips (306) to be located around the perimeter ofthe structure. The support chips, like transverse impedance amplifiers,could be arrayed on one chip and routed to the detectors in a number ofways that are known to those familiar with the art of chip layouts andintegrating hybrid chip layouts. They could also be connected throughvia holes in the substrate. Passive or active chip cooling techniquescould also be used with this configuration.

FIG. 3 illustrates an embodiment of one transceiver of a matching pair,where an array of parallel driven clustered elements grouped in aconfiguration (300) that can be easily transferred optically onto acorresponding detector array (304) using the laser source technology,such as that described in U.S. Pat. No. 7,949,024. The individualclusters of elements are themselves arrays of single elements (308),each cluster driven with their own source provide a powerful lasersource which overcomes the design problem of link budget and relatedtolerances by an abundance of power allowing a large “blur” spot (312)to be imaged across a detector's position allowing a loose alignmenttolerance from board to board. This may enhance plug and playarchitectures for optical communication between circuit boards.

Intensity Modulation

Binary weighted arrays from technology described in commonly assigned USpatent Publication No. 2011/0148328 A1, formed within each of theclusters (308) of FIG. 3 may be used to encode additional data into eachchannel by using digital intensity modulation (Amplitude Shift Keying)for any reasonable number of sub-clusters that could be fit into onecluster and imaged onto the detector. Thus, binary data may be encodedby associating intensity levels with bit positions in the binary data.In one embodiment, the least significant bit (“LSB”) is associated withthe lowest intensity level. The number of bits that can effectively beencoded is therefore primarily dependent upon the receiving end havingan LSB signal greater than the minimum link budget and the accuracy ofthe level discrimination circuitry. The diffuser element mentioned aboveis ideal for distributing the different power levels of each emittersub-cluster evenly over the detector blur spot.

VCSELs which have higher frequency responses or become faster as theircurrent bias increases, until approaching power rollover, may enhanceintensity modulation. VCSELs prefer to be turned fully on for higherspeed capability. Normally, intensity modulation is achieved by using ananalog signal level to achieve a different intensity level from thelaser and thus lower levels would slow down the entire data transmissionsystem. Turning on different arrays to their highest bias (so as toreduce distortion) and allowing the selected groupings to be used tochange the intensity levels, allows very high bandwidths to be achievedusing intensity modulation.

FIG. 4 illustrates an individual cluster grouping that has been dividedinto three separate binary weighted sub-clusters. The laser output ofeach sub-cluster increases, in a binary fashion, by either doubling theoutput of a single element or by adjusting the number of elements toincrease the power of the sub-cluster in a binary fashion. Eachsub-cluster is controlled by its own driver source which is independentfrom the other sub-clusters and their drivers. In this manner anycombination of bits (sub-clusters) can be controlled and thereby encodedduring each clock pulse. Turning on different sub-clusters orcombinations thereof during the same pulse timing would representincreased intensity levels which could be identified by a leveldiscrimination circuit as different encoding levels. In this case group(400) has 2 VCSEL emitters, group (402) has 4 VCSEL emitters and group(404) has 8 VCSEL emitters. It is assumed that each of the emitters inthis example has close to the same power output as its neighbors.Holographic optical element (406) distributes the hotspots to a moreintensity uniform mixed beam and lens (408) semi-collimates the outputof whichever groups of arrays are turned on in a single pulse.

As the varying groups are turned on the following data information canbe directed through beam intensity levels provided the detector has thedynamic range to detect differences between the least significant bit(LSB) level and the intensity level of the most significant bit (MSB):

-   -   000—No groups on during clock pulse    -   001—only group (400) is turned on during clock pulse    -   010—only group (402) is turned on during clock pulse    -   011—group (400) and (402) are turned on during same clock pulse    -   100—only group (404) is turned on during clock pulse    -   101—group (400) and (404) are turned on during same clock pulse    -   110—group (402) and (404) are turned on during same clock pulse    -   111—group (400), (402) and (404) are turned on during same clock        pulse

These configurations allow eight separate data codes to be relayed withone pulse. The preferred embodiment could use this intensity modulationtechnology but it is not necessary. Intensity modulation may also beachieved, for example, without defining groups or by having a one-to-onerelationship between groups and emitters.

An additional embodiment would employ wavelength-division multiplexingor dense wavelength-division multiplexing, with each particularwavelength having bit string information encoded on each of therespective pulses for that wavelength, or other optical multiplexingschemes, such as orthogonal frequency division multiplexing, where anumber of closely spaced orthogonal sub-carrier signals are used tocarry data. A device of this nature is capable of an extremely high datatransfer rate. Furthermore, frequency doubling is not required in thisembodiment. Frequency adding may be employed to achieve longer, eye-safewavelengths, which is an important factor when high powered laserpropagation is employed.

In another embodiment, any number of wavelengths or beams produced byany number of light sources and/or emitter chips may be combined by oneor more optical elements to form a highly resolved data pulse. Such adevice is capable of potentially unlimited bit information capacity,subject only to the size, focal length, and distance of the combininglens and the number of subgroups that can be defined according to thelimits of the dynamic range of detection.

Beam Steering

In an embodiment, an array or cluster of photonic elements behind alens, such that beams emitted from the photonic elements strike the lensat varying positions, providing directivity. Beam steering may beachieved by selectively activating an element of the array. This allowsfor non-mechanical optical alignment, thus reducing or eliminatingexcessive gimbal movement, saving energy and increasing reliability.Beam scanning may also be achieved through use of this technique. Bothone-dimensional and two-dimensional directivity may be achieved by theuse of one-dimensional or two-dimensional arrays, respectively. Inaddition, 360° coverage may be achieved by employing multiple sectors,e.g. a hexagonal, spherical, or other three-dimensional arrangement ofoutward-facing arrays.

Optical Switching in a Data Center Environment

Additional embodiments allow for optical switching applications thatemploy an array of photonic elements behind a lens. Narrow beams may bepreferred in this embodiment. In a data center rack, an optical switchemploying this technique may be placed such that narrows beams emittedfrom the switch may reach defined positions within the rack. Forexample, the switch may employ a multiple lens array and be placed atthe top of the rack, as seen in FIG. 5. In one embodiment, equipmentrack (500) may contain in its interior optical switch (502) mounted tosurface (504), which may be the ceiling of the rack. Detectors (508) maybe mounted to surface (506), which may be interior to the rack or a wallof the rack. Optical switch (502) and detectors (508) are placed suchthat optical communications between the switch and the detectors are notdisturbed, for example by maintaining line of sight between the opticalswitch (502) and the detectors (508). This arrangement allows forprecise data shower beams to reach server connections at definedpositions within the rack, enabling a cable free rack. While a ceilingarrangement is illustrated in FIG. 5, the optical switch (502) could bemounted on the floor of the rack or anywhere in-between the floor andthe ceiling, depending on the configuration of the rack and what portionof the rack provided the clearest line of sight for the beams.

Other embodiments allow for various network topologies, employing a widevariety of link geometries such as start, daisy chain, ring, or mesh.Various factors such as the arrangement of racks, airflow, andelectrical cabling may create impediments to line of sight, but theseimpediments may be overcome by selecting suitable link geometry. Theappropriate geometry may involve not only the network topology, but alsocorrect positioning in both the horizontal and vertical dimensions. Forexample, the device pictured in FIG. 6 may be employed to position thephotonic array a suitable distance above a rack. Optical switches ortransceivers (600) may be mounted to a multi-sided structure (602),which is shown having six sides, but could be configured to have manydifferent configurations with many different numbers of side. Themounting system may support alignment or reorientation of the opticalswitches or transceivers (600). For example, as shown in the lowerportion of FIG. 6, the multi-sided structure (602), shown from a sideperspective, may be connected to rack (606) by support structure (604),which may allow for rotation or height adjustment. Further the opticalswitch (600) may be formed from arrays of sub-arrays with a lenspositioned in front of the groupings of sub-arrays in order to steer abeam emitting from switch (600) to a specific position where thedetection might be located. This may allow another degree of freedom andallow automatic alignment of beams. Theses subgroups of arrays incombination with the correct lens design may cover a small area in whichautomated beam alignment may take place by a scanning and receivingscheme.

Use of embodiments within the data center allow for improved linkbudget. More precise alignment of the beams allows for a narrower fieldof view and relaxed power requirements, which in turn allows for higherbandwidth. When used within the data center, embodiments are capable ofachieving at least gigabit/second throughput on the free space opticalcommunication network.

On a macro scale, not all frequencies propagate well in the atmosphere.Suspended particulate matter, such as fog, dust, rain, or snow, may alsoimpeded light-wave propagation. However, in a data center mostfrequencies propagate well enough and particulate matter is not usuallyan issue.

High aggregate bandwidth, 40 Gb/s or higher, may be achieved throughmultiplexing. Wavelength-division multiplexing allows for multiple lightwavelengths to be placed on the same optical path. Where the sourceconfiguration is overlaid, greater power density results. The sourceconfiguration may also be tiled, allowing for angular separation. Anembodiment may employ frequency multiplexing or spatial and angularmultiplexing with a single wavelength, as depicted in FIG. 7. Forexample, stacked emitter (700) may emit laser output at multiplefrequencies, striking the surface of lens (706) and following opticalpath (708). Non-stacked emitters (702) and (704) may emit frequencies ofthe same or different wavelengths, and their output strikes lens (706)and follows optical paths (710) and (712), respectively. The beam sizedetermines both spatial channel density and angular resolution.

High Speed High Power Arrays for Optical Switching

Arrays of VCSEL devices may be used in a high speed switching matrix.Information may be fed to the switch by a single source such as a 100Gb/s fiber connection. Each packet of information that needs to berouted is separated by a standard routing chip that routes packets tothe appropriate output channel.

The signal from the output channel may be amplified by a high speedcurrent driver which is connected to a single VCSEL device, or an arrayof VCSEL devices. Each of these, in turn, is part of a larger array, thesize of which defines how many channels are available in the overallswitching network.

The output of the laser devices are separated by a controlled distancethat is imaged through an optical element onto a pattern of opticalelements, such as lenses, arrays of lenses, or optical fibers. Thesignal of each sub-element is then injected into that single optical orfiber channel. Additional optical elements that could be deployed withinthe path of a laser beam for a variety of purposes include diffusers,mirrors, and MEMS devices, to name a few.

The optical or fiber channels also form an array. The output of thisarray may be handled in at least two ways. First, it may be directedonto an array of detectors, with each detector signal being convertedback into an optical signal and injected into a fiber. The fiber may goto an optical plug such as a single fiber plug, or any other type ofoptical termination. Second, the output of the optical switching arraymay be injected directly into an optical element or fiber.

In order to end up with a detectable signal, the link budget of theconfiguration must be analyzed. In many cases there is insufficientpower at the start of the system. Extra power will enhance the signalquality and improve the bit error rate. It may therefore be desirable tooperate each sub-element at as high a power level as practical.

An embodiment is depicted in FIG. 8. A number of VCSEL arrays (802),(804) may be mounted to a surface (800). Output from the VCSEL array(802) passes through lens (806), striking ball lens (808), which may becoupled to a channel (812), which may be an optical fiber. Likewise,output from the VCSEL array (804) passes through lens (806), strikingball lens (808), which may be coupled to a different channel (810). Thelines depicted in FIG. 8 representing the output do not represent raytracing, but rather only a positional imaging relationship.

Eye Safe Optical Networks for Home and Office

Numerous applications may make use of the herein disclosed form of freespace optical communications. For example, using a transmitter to spreadpower density over a large area in which the power density is eye safe,one or more emitters/receivers may be embedded in a table top, with alight signal coming up to a counter or surface with a protective clearcover so that mobile devices which have an emitter/receiver on orembedded in the device, may be placed on top of a table andautomatically linked to a 1G to 10G data source. Numerous other physicalconfigurations are possible involving emitters/receivers being placed inother locations in or around a surface in the room for the same purpose.For example, a laser emitter cluster may emit a laser beam to an opticalelement shaped as a clear planar surface having a first side and asecond side, where the first side receives the laser beam and spread anoutput of the laser beam over an area of the second side sufficient toreduce a power density of the laser beam to an eye safe level.

Embodiments ease this type of operation because no aligning is necessarydue to the wide signal coverage area. In addition, there are nohardwired connections to get lost, mangled or stolen. Public accessnetworks of this type are much easier without cables. Transmitters coulduse THUNDERBOLT technology from INTEL or other protocols. Thesetransmitters need more power for larger area of transmission.

Free-space optical communications over a distance greater than a meterrequires a limited optical power density for eye safe operation, incombination with wider area coverage for ease of reception positioning.These requirements have limited the devices capable of offering thehigh-power and high-speed required for a wider field of use.

With the sufficient bandwidth and power density enabled by thehigh-powered, high-speed device offering a wide field of use for theoptical signal, a single link may transmit data over multiple channelsor may serve many users simultaneously. An array of sub-grouped arraysbehind a lens may be switched so that separate beams can be positionedrelative to separate areas. Detectors arrays, also called Free-SpaceOptical MIMO (Multiple Input-Multiple Output) detectors, may besequenced to identify where signals need to be sent and send signals tothose specific areas. Multiple sub-grouped arrays may be functional inany one time sequence, which allows simultaneous communication links tomultiple users. Another embodiment for multiple users may employwavelength division multiplexing by the same MIMO detectors scheme asdescribed above, but with filtered inputs sensitive to multiplewavelengths, and the ability to sense and respond using multiplechannels at different wavelengths for both input and output.

One or more transmitters may be connected to a data source such as afiber optic cable, a high speed Ethernet cable, or a video source.

A transmitter may consist of a signal input interface, the packagedVCSEL array, VCSEL driver, and control and amplification electronics,and may also include receiver components and electronics making atransceiver and appropriate beam-shaping optics, all in a commonhousing. Other components may include an optical component for spreadingthe optical power density to eye safe levels and a lens for controllingbeam diameter and dispersion of the beam in the free space area.

The transmitter and receiver housing may be pointed towards each otherusing a simple plastic molded eyeball type socket scheme. Thetransmitter or transceiver may be pointed toward the receiver ortransceiver by an adjustable gooseneck lamp type configuration. Thetransmitter and receiver may each operate from a simple low voltage DCpower supply or even batteries. The transmitter/transceiver may beinstalled in conjunction with other ceiling-resident utilities such aslighting, safety/security sensors, video cameras and security claxons.

The VCSEL array may be operated as a group (ganged), or as anaddressable array where one or more sub-arrays, each of one or moreelements, may be independently signal-driven and moved across the totalarray positionally.

The transmitter may operate in “broadcast” mode delivering a wide beamof data to one or more receivers.

The transmitter may operate in “beaming” mode delivering a narrow beamto one or more receivers.

The transmitter may operate in “panning” mode where sub-arrays areoperated in sequence across the VCSEL array which translates into anangular motion in free-space.

The system may be configured as a simplex (one-directional) link, or asa full duplex (bi-directional) link. In the latter case, there is aVCSEL array and one or more detectors at each end of the optical link.

When detector arrays are used, the detector array or sub-array havingthe strongest signal may be selected as indicating the nearesttransmitter for preferential attention, for “hand-off” to a neighboringtransmitter, or to accommodate moderate angular misalignments of thereceiving optics away from the desired transmitter.

Transmitters may be placed in a ceiling of an office, with each onespaced at a distance such that they have sufficient coverage at thereceiver without excessive overlap of signal.

Transmitters may be placed centrally on a vertical support, such as alight pole, with each transmitter covering its own angular sector ofspace.

The receiver may consist of a light collecting device, a detector,amplifying electronics and a suitable output interface.

The light collecting device may be an imaging lens or a non-imagingdevice such as a cylindrical parabolic concentrator.

At the receiving detector, the data may be conveyed to a local datatransport scheme such as fiber optic, Ethernet, digital video cable oreven wireless such as Wi-Fi.

The receiver may also be incorporated directly into a digital switch orrouter which distributes the ultra-high bandwidth to multiple localusers over cable or wireless.

The receiver may be integrated directly to the component needing thehigh bandwidth link.

Because of the likely asymmetry of the bandwidth required for thedownlink versus the uplink, alternative cable or wireless uplinks may beused such as Wi-Fi, BPL, Ethernet, etc.

An optical filter for the transmitter wavelength may be used at thereceiving end to suppress all other wavelengths other than that of thetransmitter needed. Multiple wavelength links in a single transmittermay be used.

Polarized VCSEL arrays may be used in conjunction with polarized filterson the receivers to help eliminate stray reflection signal interference.

Optical limiting path blinders at the receiver may eliminate strayreflective signals coming in at different angles other than the incidentsignal.

Multiple transmitters or transceivers may be used from differentlocations allowing an triangulational positioning grid for best signalreception or to prevent signal blackout from moving objects.

Window filters may be used for securing data from leaving building.Transmitters or transceivers may be mounted on walls, floors, ceilingsor objects. Transmitters or transceivers may be mounted in attics crawlspaces or hard to access point to point areas. Transmitters ortransceivers may be mounted in pipes. Transmitters or transceivers maybe mounted in chimneys.

Additional Embodiments

Numerous additional embodiments are possible. For example, each matchingpair of a transceiver anywhere from one to thousands of pairs may usethis technology in any number of layout configurations.

Clusters of elements may be driven as a single channel or configured forintensity modulation of each transceiver channel.

A bottom emitting array is disclosed in U.S. Pat. No. 7,949,024.However, a bottom emitting array in a flip-chip configuration or a topemitting array or grouping of top emitting arrays may be used for themulti-element emitter devices.

A single duplex transceiver may be used for board to board free spaceoptical communications using arrayed VCSEL technology mentioned in U.S.Pat. No. 7,949,024.

A 2D pattern of almost any shape may be formed instead of merely asquare or rectangular pattern which might function better using roundoptical elements.

A 1D array with any number of clusters or emitters could be used in aconfiguration other than single or 2D.

Any number of patterns could be used to form the clusters and to imageonto the same pattern of arrays.

The 1D or 2D arrays could be used as a backplane to select which channelwill receive the data pulse by selecting a different emitter or emittersto transfer the data to those select channels. When data needs to besent to a specific channel the appropriate emitter would be chosen whichis already in alignment to that channel through the imaging orprojecting lens in front of the whole array. Embodiments could also beused at longer distances for high speed data communications applicationswith the appropriate imaging optics

Emitter arrays mentioned above in FIG. 3 (300) could be formed from thesame high speed and high power technology or, as noted above, flipchipped to a substrate instead of designed onto the substrate.

Flipped chipped emitters could be at a different wavelengths allowingWDM capability for emitters and appropriate filtering of wavelengths fordetectors.

High power beams could be spread over a larger receiving area oroverlapping with other emitter beams onto an area that may have multipledetectors. Filters covering the detectors could be used in conjunctionwith multiple wavelength emitter chips to separate the signals of thoseoverlapping beams from different wavelength emitter clusters.

Transmitters or transceivers may be used for high speed long haulapplications.

Transmitters or transceivers may be used between satellites.

Transmitters or transceivers may be mounted on telephone poles orrooftops of buildings.

Transmitters or transceivers may be mounted on vertical poles for bettertransmission angles.

The receiver portion of a transceiver may have a photovoltaic or “solarcell” situated around the detector in able to recover all optical powerpossible, or at least excess laser energy, when the bundle of laserbeams is configured to over-fill the collection lenses and detectors inan area so to achieve easier alignments.

The photovoltaic device mentioned above may be a source of power whichis transmitted optically from a base station or device in order totransmit power and/or data communications.

In one embodiment, linear arrays with any number of rows may be employedfor data transmission. Any number or all of the rows may besimultaneously on, even if the pulses have the same or similarwavelength. The output position of each row, in relation to the otherrows, adds a dimensional element to wavelength-division multiplexing ordense wavelength division multiplexing.

In another embodiment, a one-dimensional array is used as to produce asingle wavelength pulse, which is combined with other sources of thesame or different wavelengths. The combined wavelength's output pulseintensity is scanned in a vertical and horizontal manner, enabling datatransmission.

In another embodiment, the speed and data rate of VCSEL arrays can beincreased by employing flip chip technology and a design for high-speedarrays with a waveguide being formed around each sub-array or element,as described in U.S. Pat. No. 7,949,024.

What is claimed:
 1. A multi-channel optical communications device forfree-space optical communications capable of non-mechanical beamdirectivity, the device comprising at least two symmetric, oppositelyfacing transceiver systems, each comprising: a transmitting lens; anoptical diffuser positioned behind the lens at a distance equal to afocal length of the lens; a plurality of laser emitter clusterspositioned behind the optical diffuser, each of the plurality of laseremitter clusters configured to emit a laser beam bundle, each laseremitter cluster positioned relative to the transmitting lens so theemitted laser beam bundle travels a distinct optical path through theoptical diffuser and the transmitting lens, wherein the optical path isseparated and angularly-shifted from optical paths of other laser beambundles; and circuitry configured to activate one of the plurality oflaser emitter clusters based on a desired optical path for the laserbeam.
 2. The device of claim 1, wherein the plurality of laser emitterclusters are configured in a linear array.
 3. The device of claim 1,wherein the plurality of laser emitter clusters are configured in atwo-dimensional array.
 4. The device of claim 1, wherein the opticaldiffuser is a holographic diffuser.
 5. The device of claim 1, whereinthe optical diffuser is configured to distort the laser beam bundles toproduce lines or other geometric figures at fixed angular distances fromeach other.
 6. The device of claim 1, wherein a first laser emittercluster forms a laser beam bundle having a first geometrical pattern,and a second laser emitter cluster forms a laser beam bundle having asecond geometrical pattern, wherein the first geometrical pattern andthe second geometrical pattern are angularly separated.
 7. Amulti-channel optical illumination device for optical sensing with animaging array or detector array capable of non-mechanical beamdirectivity, the device comprising at least two symmetric, oppositelyfacing transceiver systems, each comprising: a transmitting lens; anoptical diffuser positioned behind the lens at a distance equal to afocal length of the lens; a plurality of laser emitter clusterspositioned behind the optical diffuser, wherein one or more laseremitter clusters among the plurality of laser emitter clusters are eachconfigured to emit a laser beam bundle each laser emitter clusterpositioned relative to the transmitting lens so the emitted laser beambundle travels a distinct optical path through the optical diffuser andthe lens, wherein the optical path is separated and angularly-shiftedfrom optical paths of other laser beam bundles; and circuitry configuredto activate one or more of the plurality of laser emitter clusters basedon one or more desired optical paths for the laser beams.
 8. The deviceof claim 7, wherein the plurality of laser emitter clusters areconfigured in a linear array.
 9. The device of claim 7, wherein theplurality of laser emitter clusters are configured in a two-dimensionalarray.
 10. The device of claim 7, wherein the optical diffuser is aholographic diffuser.
 11. The device of claim 7, wherein the opticaldiffuser is configured to distort the laser beam bundles to producelines or other geometric figures at fixed angular distances from eachother.
 12. The device of claim 7, wherein a first laser emitter clusterforms a laser beam bundle having a first geometrical pattern, and asecond laser emitter cluster forms a laser beam bundle having a secondgeometrical pattern, wherein the first geometrical pattern and thesecond geometrical pattern are angularly separated.
 13. A multi-channeloptical illumination device for optical sensing with an imaging array ordetector array capable of non-mechanical beam directivity, the devicecomprising at least two symmetric, oppositely facing transceiversystems, each comprising: a transmitting lens; an optical diffuserpositioned behind the lens at a distance equal to a focal length of thelens; a plurality of laser emitters positioned behind the opticaldiffuser, wherein the plurality of laser emitters are configured ingroups sufficient to enable a group to emit laser beams, each grouppositioned relative to the transmitting lens so the emitted laser beamseach travel a distinct optical path through the optical diffuser and thelens and produce illumination beam bundles distinct from laser beambundles emitted by any other group, wherein each illumination beambundle is separated and angularly-shifted from other illumination beambundles; and circuitry configured to activate one of the groups based ona desired optical path for the laser beam of the group.
 14. The deviceof claim 13, wherein the optical diffuser is a holographic diffuserconfigured to distort the laser beams of the groups to produce lines orother geometric figures at fixed angular distances from each other. 15.The device of claim 13, wherein a first set of laser emitters among theplurality of laser emitters are grouped so the laser beams of a firstgroup form a first geometrical pattern and a second set of laseremitters among the plurality of laser emitters are grouped so the laserbeams of a second group form a second geometrical pattern, the firstgeometrical pattern being angularly separated from the secondgeometrical pattern.
 16. The device of claim 1, wherein each transceiversystem further comprises two or more receiver lenses and correspondingdetector/amplifier pair elements.
 17. The device of claim 16, whereinthe plurality of laser emitter clusters and the detector/amplifier pairelements have a shared substrate.
 18. The device of claim 17, whereineach of the two or more receiver lenses and correspondingdetector/amplifier pair elements are positioned at a periphery of theshared substrate and the transmitting lens, the optical diffuser and theplurality of laser emitter clusters are positioned towards a center ofthe shared substrate.